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Peebles 1982

Peebles 1982 . Large Scale Background Temperature and Mass Fluctuations Due to Scale-Invariant Primeval Perturbations. Amruta Deshpande 9/17/9. A Cold WIMP Model. W = 1, L = 0 & WIMP mass, m x > ~ 1 keV On top of primeval pertubation spectrum || V

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Peebles 1982

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  1. Peebles 1982 Large Scale Background Temperature and Mass Fluctuations Due to Scale-Invariant Primeval Perturbations AmrutaDeshpande 9/17/9

  2. A Cold WIMP Model W = 1, L = 0 & WIMP mass, mx > ~ 1 keV On top of primeval pertubation spectrum || V Density Fluctuation Power Spectrum, P(k) RMS Mass Fluctuation, dM/M Autocorrelation Length, x Size of Temperature Fluctuation, dT/T

  3. Overview • Important Model Features and Motivations • Calculations • Discussion of Findings

  4. Basic Assumption 1 • Adiabatic Perturbations with Scale-Invariant Power Spectrum: • P(k) k • Equal amount of density fluctuation at any length scale (scale invariant) • Primeval spectrum • Spectrum at small k or large scale

  5. Basic Assumption 2 • mx Dominates (W = 1) • Needed to make small scale (smaller than Jean’s length) perturbations grow before decoupling • Baryon-only universe, inconsistent with • P(k)k • linear growth factor off by 8 orders of magnitude

  6. How Heavy? Limit on mx: • Particle Velocity Distribution: • [ exp(mxvc/kTx) ± 1 ] -1 • distribution  rms peculiar velocity  rms displacement, r

  7. Power Spectrum • Small k: P(k) k • Large k: P(k) k-3

  8. Background Temperature , for q << 1 radian

  9. RMS Mass Fluctuation • From: • Get: • a2 = 3.5x10-6 Thermal motions 8 Mpc R-2 ~ primeval

  10. Summary of Results / Implications • a2 = 3.5x10-6 • dT/T ~ 5x10-6

  11. Conclusions • Adding a dominant, massive, weakly interactive component to the universe allows perturbations to grow sufficiently, to explain to the distribution of galaxies seen today.

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